Intel Core i7 Goes Mobile – Core i7-920XM ‘Clarksfield’ CPU Review

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Power Consumption & Intel Turbo Boost

When we read about Intel’s Power Boost Technology implemented on the new Core i7 Mobile processors, we instantly thought of one benchmark to test the enabling and disabling of cores; Cinebench R10. Cinebench allows you to run the benchmark in single or multi threaded modes. We took a number of power consumption readings by plugging the Clevo W870CU into our Seasonic PowerAngel to measure the Watts being consumed. We measured how much power was being consumed while the system was at idle and charging the battery, but then we simply removed the battery for the rest of the readings so it was not a factor in our readings.

 

 Cinebench R10 Single Core Test
 Beginning Consumption  42W
 Observed Mode Consumption  74W
 Observed Max Consumption  84W
 Observed Max Frequency  3.0GHz
 Cinebench R10 Multi Thread Test
 Beginning Consumption  42W
 Observed Mode Consumption  92W
 Observed Max Consumption  102W
 Observed Max Frequency  2.0GHz

 

These readings were taken without the battery installed. We observed that the system jumped from 42 watts to the max reading right away. Then it seems the system settled in on the value we termed the ‘mode’ because it was the reading that was observed the most. The chart above shows that Intel’s Turbo Boost Technology definitely turned on for the single core test in order to sustain a frequency of 2.9-3.0 GHz throughout most of the duration of the benchmark.

We then ran the multi thread benchmark in Cinebench and observed that with all 4 cores running at max, the system did not increase the CPU frequency from the rated core speed of 2.0GHz most likely due to the heat that was being output since the system will attempt to keep the max TDP of the 920XM processor at 55W. We did observe a roughly 60W jump when we first started the multi thread test, but then the system settled in at 92W which was a 50W increase from idle.

We found this test to be very interesting since it definitely demonstrates that Intel’s Turbo Boost Technology does its job! Kudos to Intel for developing such a dynamic Core i7 mobile processor!

 

 Battery & Idle
 Idle with no battery  39W
 Idle with battery  80W
 Idle Frequency  1.2GHz
 Internet Browsing
 Max Consumption  58W
 Max Frequency  2.8GHz
 Gaming
 Mode Consumption  122W
 Max Consumption  132W

 

Here we see the Clevo W870CU consumes about 40W just to charge the battery. So for the rest of the readings, you would need to add 40W in order to know how many watts you should be prepared to consume if on the road gaming is in your mind. Bringing the GPU up to speed definitely increases the power consumption, but only by another 30W from our highest Cinebench consumption reading.

So the bottom line here is the rough max consumption of our test system was ~172W if you are charging your battery while gaming. This is great news as you can pick up a ~$30 200W power inverter and game on the road or simply watch a movie and not need to worry about your battery life!

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